#!/usr/bin/env python   
#coding=utf-8   
#python version 4  
class stack:  
    def __init__(self,list=None):  
        self.contain = list   
        self.msize=100;  
        self.top = 0;  
    def getTop(self):  
        if(self.top>0):  
            return self.contain[self.top-1]  
        else:  
            return None  
    def getLength(self):  
        return len(contain);  
    def push(self,str):  
        if(self.top==self.msize):  
            return -1  
        self.contain.append(str)  
        self.top=self.top +1  
    def pop(self):  
        try:  
            res=self.contain.pop()  
            return res;  
        except IndexError:  
            return None  
          
  
  
li = [1,'51','15']  
st = stack(li)  
va='5'  
print st.pop()  
print st.pop()  
st.push('fdef')  
print st.pop()  
print st.pop()  
